The present invention relates generally to network communications and, more particularly, to admission control in a network device.
In computer networks, a number of network stations are typically interconnected via a communications medium. For example, Ethernet 802.3 is a commonly used local area network (LAN) scheme in which multiple stations are connected to a shared or dedicated serial data path. These stations often communicate with a switch or some other network device located between the data path and the stations connected to that path. The switch typically controls the communication of data and includes logic for receiving and forwarding data frames to their appropriate destinations.
When all of the stations connected to the network are simultaneously operating and transmitting data at high speeds, data traffic on the switch may become heavy. Accordingly, some switches may drop data frames after a congestion condition is detected. In this case, the dropped data frames are not forwarded to their intended destinations. One drawback with conventional switches that drop data frames is that the switch randomly drops the data frames without determining the nature of the data in the respective data frames.
There exists a need for a mechanism in a network device that selectively drops data frames when a congestion condition exists. This and other needs are met by the present invention, where a multiport device receives a data frame and identifies the type of data included in the data frame. The multiport device then determines whether to perform admission control on the received data frame based on the availability of resources on the multiport device and the type of data included in the data frame.
According to one aspect of the invention, a network device that controls communication of data frames between stations is provided. The network device includes a plurality of receive ports configured to receive data frames from the stations. The network device also includes data frame processing logic that determines whether admission control is enabled. The data frame processing logic also determines whether to drop one of the received data frames based on whether admission control is enabled and information included in the received data frame.
Another aspect of the present invention provides a method in a network device that controls communication of data frames between stations. The method includes receiving data frames from the stations and determining whether a first received data frame is associated with establishing a connection between a first device and a second device. The method also includes dropping the first data frame when the first data frame is associated with establishing the connection.
Other advantages and features of the present invention will become readily apparent to those skilled in this art from the following detailed description. The embodiments shown and described provide illustration of the best mode contemplated for carrying out the invention. The invention is capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings are to be regarded as illustrative in nature, and not as restrictive.